In a geometric progression, the first term is 153 and the sixth term is (frac{17}{27}). The sum of the first four terms is
-
A.
(frac{860}{3}) -
B.
(frac{680}{3}) -
C.
(frac{608}{3}) -
D.
(frac{680}{3})
Correct Answer: Option B
Explanation
a = 153 – 1st term, 6th term = (frac{17}{27})
nth term = arn
Sn = a(1 – rn) where r
6th term = 153(frac{1 – 0.4^4}{1 – 0.4})
= (frac{680}{3})